The present invention relates to a liquid crystal element, and in particular to an in-plane electric field mode liquid crystal element.
Liquid crystal elements, and particularly liquid crystal display devices, are used not only in monitors for notebook computers and desktop computers but also in the display portion and portions related to the display portion of various apparatuses, including the viewfinder of video cameras and in projections displays, and recently they have come to be used as the display portion of televisions as well. Moreover, they are also utilized as optoelectronic-related elements such as optical printer heads, optical Fourier transform elements, and light valves.
Presently, liquid crystal elements are most often used in display devices, and typical liquid crystal display modes include the TN (twisted nematic) mode, the VA (vertical alignment) mode, and the IPS (in-plane-switching) mode.
Of these, the IPS mode, which is also called the in-plane electric field mode and the comb electrode mode, is characterized in that the liquid crystal molecules are orientated substantially parallel to the substrate surface so that by generating an electric field parallel to the substrate surface the liquid crystal molecules are rotated within the substrate surface, and therefore there are few changes in brightness due to the viewing angle direction, which in turn results in excellent viewing angle properties (xe2x80x9cLiquid Crystal Display Technologiesxe2x80x9d, pg. 4, published by Sangyo Tosho; also, JP H10-206867A).
In addition to the above, as an improved version of the IPS mode there is also the FFS (fringe field switching) mode, in which the electrode interval is narrowed and driving is performed using an oblique electric field, and the HS (hybrid switching) mode, in which electrodes are formed at opposing sides of the substrate and an oblique electric field is utilized. It should be noted that, strictly and purely technically speaking, both of these modes include features not present in the IPS mode, however, they share the object, configuration, and effect of the invention of the present application described below (or they can utilize the concept of the invention of the present application). For this reason, in the present specification, and especially in the scope of the claims, IPS mode or in-plane electric field mode also includes the FFS and HS modes.
For comparison, these three modes are illustrated in FIG. 1. In the drawing, numeral 1 is an array substrate, numeral 2 is an opposing substrate, numeral 3 is a liquid crystal, numeral 6 is a source line, numeral 7 is a scanning line, and numeral 17 is a thin film semiconductor. However, because the technical contents of these modes are so-called widely known technologies, a description of them has been omitted.
The filling of liquid crystal into the liquid crystal panel of not only the IPS mode is shown in FIG. 2. First, a belt 201 of sealing resin is printed thinly around the four corners of a single glass substrate 2 by printing, and the glass substrate 2 is aligned with a separate glass substrate 1 to form a cell. Next, liquid crystal is vacuum loaded into the cell through an injection port formed by leaving out a portion of the sealing resin, after which a UV curable resin 202 is applied to that injection port and the liquid crystal is sealed in. This is followed by curing the resin for sealing the port by UV light irradiation.
With this method, however, bubbles 151 or foreign matter 15 may be left in the gap of the injection port between the two glass substrates when applying the UV resin. If bubbles or the like are left, then, as shown in FIG. 3, the bubbles or foreign matter, for example, remaining in the UV curable resin scatter and refract or absorb the UV light during UV irradiation, and the UV curable resin behind the bubbles seen from the direction of UV irradiation is not sufficiently irradiated with UV light. The result is that not only does the UV resin at insufficiently irradiated portions simply remain uncured in this state, but the uncured resin disperses into the liquid crystal when used, and thus becomes a factor that lowers the long-term reliability of the liquid crystal element. Furthermore, countering this by irradiating the UV light from various directions complicates the process.
Also, continuously using a TFT liquid crystal display device of the IPS mode may cause display uniformities where, for a black-and-white display, what should originally be displayed white appears as black dots. These so-called black dot nonuniformities must be eliminated because they can significantly reduce the display quality. A method for countering and eliminating these black dot display nonuniformities is mentioned in JP-H10-206857A. According to this method, black dot nonuniformities are generated by an electrochemical reaction occurring at a cracked portion of the protective layer between the pixel electrode and the source signal line, which lowers voltage holding ratio in the liquid crystal layer due to the creation of ionic material and changes the arrangement of the liquid crystal. (Consequently, depending on whether the display mode is so-called normally white or normally black there can also be white dot display nonuniformities. Furthermore, in color displays, the color of display nonuniformities is not limited to black and white. For this reason, the concept referred in the present specification as xe2x80x9cblack dot display nonuniformities,xe2x80x9d for example, also encompasses xe2x80x9cwhite or colored dot display uniformities resulting from a drop in voltage holding ratio.xe2x80x9d) The result is that black dot nonuniformities can be eliminated by making the protective layer thicker than the electrode or forming an organic polymer protective layer.
The following is a description of a conventional liquid crystal display device of the IPS mode, with reference to the drawings.
FIG. 4 schematically illustrates a plan view of a pixel of the array substrate of a liquid crystal display device. FIGS. 5(1) and 5(2) are views showing cross sections taken along the lines Axe2x80x94A and Bxe2x80x94B, respectively, in FIG. 4. FIGS. 6(1), 6(2), and 6(3) are views showing cross sections taken along the lines Cxe2x80x94C, Dxe2x80x94D, and Exe2x80x94E, respectively, in FIG. 1. The opposing substrate in FIGS. 6(2) and 6(3) is identical to that in FIG. 6(1), and thus has been omitted from FIGS. 6(2) and 6(3).
In FIGS. 4 and 5, numeral 5 is a common electrode and numeral 7 is the gate signal line, and these are formed in the same layer. Next, an insulating layer 8 is formed on this layer (to the liquid crystal layer side), a thin film transistor (TFT) 17 made of a semiconductor layer, a source signal line 6, and a pixel electrode 4 are further pattern-formed, and a protective layer 10 is deposited thereon, thus forming an array substrate. Orientation films 9 are formed on the array substrate and on the opposing surface side of an opposing (color filter) substrate 2 that is in opposition to the array substrate, and furthermore a liquid crystal layer 3 is formed between these substrates, thus forming a liquid crystal display panel. FIG. 6 is a slightly more detailed cross-sectional view of the same, the contents of which will be described later.
As shown by these three drawings, unlike a TN-type liquid crystal panel, the electrodes in an IPS panel are in the same plane.
Also, the electrode connected to the drain of the thin film transistor is called the pixel electrode, and the electrode that is not connected to the drain is called the common electrode.
However, extremely fine processing is required in the manufacturing process of such a liquid crystal display panel, so contamination by foreign matter during manufacturing causes short circuits at the intersecting portions of the gate signal lines and the source signal lines and at portions where the gate signal lines are close to the common electrodes, for example, and this becomes a major factor that lowers production yield.
That is to say, when the gate signal line and the common electrode are formed on the same surface, as shown in FIGS. 4 to 6, there is the possibility that after the electrode material has been deposited by a normal sputtering technique, for example, and patterning is performed using photolithography, if the foreign matter 15 included in the material for the resist, for example, is in sites where the electrode material should be removed, as shown in FIGS. 7 and 8, then these sites are not exposed due to the foreign matter and spots are left which should have originally been removed and formed as separate lines or electrodes as shown in FIG. 4, but instead become continuous lines, causing short-circuits.
In general, there are usually several short-circuited spots in a liquid crystal display panel. One countermeasure is to cut off the shorted-circuited portions with a laser, for example.
However, removing short-circuited portions due to foreign matter by laser also cuts off the electrode at that spot and moreover destroys the insulating film on top of the gate electrode, thus exposing the gate electrode.
It has been found that black dot display nonuniformities occur at the exposed portion of a gate electrode when the liquid crystal display device is operated at high temperature while the gate electrode is exposed.
A conceivable cause for this is that the gate potential is negative except for when recharging in order to drive the liquid crystal layer, that is, most of the time electrons are being injected into the liquid crystal and a large number of ions in the liquid crystal are created, or ions in the liquid crystal layer gather at the exposed portion of the gate and cause an uneven distribution of ions. This mechanism is schematically shown in FIG. 9. FIG. 9 schematically shows how a substance A within the liquid crystal is ionized to Axe2x88x92 by electrons exe2x88x92 that have been injected into the liquid crystal.
Cyano-based liquid crystals have conventionally been used particularly in liquid crystal modes that achieve a wide viewing angle by applying an electric field that is parallel or oblique with respect to the substrate. However, although cyano-based liquid crystals are advantageous in increasing speed, because the liquid crystal is qualitatively easily decomposed, the amount of ions in the liquid crystal easily increases, and from this aspect there is the risk that black dot nonuniformities occur readily.
JP-H10-206857A also mentions preventing the generation of these black dot nonuniformities. According to this publication, it is preferable that the film thickness of the protective film or the insulating film 8 is at least 0.4 xcexcm thicker than the film thickness of the electrode in contact with this protective layer. With this method, however, the protective layer is destroyed, no matter how thick it is made, if a laser is irradiated to cut off the electrode to counter short-circuits, and thus black dot nonuniformities can occur.
Moreover, JP-H10-186391A proposes a method in which the specific resistance of the liquid crystal is at least 1013 xcexa9xc2x7cm, and the insulating film, which is the cause of drops in optical voltage holding ratio, is removed to so that a portion of the electrode structure generating the electric field is formed in direct contact with the orientation film.
Thus, with this method for forming a portion of the electrode structure in direct contact with the orientation film, there is a minor reduction in the size of the black dot spots compared to a case where the entire electrode is covered by the insulating film. However, with this method, the effect of reducing the black dot spots is small and is insufficient for meeting the capabilities of recent high standard displays.
Furthermore, the problem of display burn-in (when once a certain pattern has been displayed for a long time, that pattern remains even after another pattern has been switched to) becomes pronounced.
Studies conducted by the inventors have revealed the following reason for this: As schematically shown in FIG. 10, ionic is material in the liquid crystal, which are a cause of black dot nonuniformities, spread not only to the array substrate 1 side but also to the opposing substrate 2 side (color filter substrate side). Consequently, simply forming an electrode in which the insulating film has been removed at only one of the substrates (array substrate side) proves to be insufficient.
One conceivable measure to counter this would be to supply a positive electric potential with respect to the gate signal line directly from the pixel electrode, source signal line, common line, and common electrode to the liquid crystal layer to neutralize the generated ionic material. However, all of these lines and electrodes are necessary in driving the liquid crystal layer, and not only is it problematic from the perspective of display image quality for the electric potential necessary in driving the lines and electrodes to be altered by an electrode reaction with the liquid crystal, but this is also not preferable from the standpoint of long-term reliability.
Moreover, simply forming the above electrode is not sufficient for preventing black dot nonuniformities from occurring because of its small area for neutralizing and recovering ionic material in the liquid crystal.
Methods have been proposed for increasing the numerical aperture in a liquid crystal panel of the in-plane electric field mode by making the electric potential of the conductive black matrix substantially the same as that of the common electrode, or forming a conductive film of an electric potential substantially the same as that of the common electrode on the black matrix (JP H10-206867A and JP H09-269504A). However, as mentioned earlier, ionic material in the liquid crystal causing black dot nonuniformities spread not only to the opposing substrate side (color filter substrate side) but to the array substrate side as well, as schematically shown in FIG. 10, so it was not sufficient to form an electrode in which the insulating film is removed only on the side of one of the substrates (opposing substrate side).
Moreover, although these methods offered some improvement in black spot defects, they were unable to completely eliminate them during long-term continuous driving.
(Background art seen from the aspect of the problems to be solved by the invention)
Thus, there has been a need for the development of technology to securely and very reliably seal the liquid crystal injection hole (port) between the two substrates.
Moreover, although the curing period can be freely set when curing the resin by irradiating UV light, operator eye safety must also be taken into account. For this reason, there is also a need for a somewhat different resin.
Furthermore, there is a need for the development of an IPS mode liquid crystal display element and device that are inexpensive and in which there are no black displays after extended periods of use, the numerical aperture or other display properties are not adversely affected, and the manufacturing process is not complex.
Moreover, with the increase in size and price of display devices in recent years, there are cases of these devices being used for very extended periods of time. Thus, in these cases, there is a need for the development of technologies in which black display do not occur even if ions are generated for the above-mentioned reasons or when there is decomposition or hydrolysis of the liquid crystal due to user error or natural radiation.
It is an object of the present invention to solve the above problems.
The first major inventive group includes two inventive groups. The first inventive group of these is characterized in that a resin of a viscosity at 20 Paxc2x7s or less, and preferably 10 Paxc2x7s or less, is used to seal the injection port through which liquid crystal is loaded between the substrates during production of a liquid crystal element in which liquid crystal is sandwiched between two substrates.
Furthermore, to lower the viscosity of the resin, it is warmed by infrared light, for example, to 80 to 50xc2x0 C. and preferably to 80 to 90xc2x0 C. from the standpoint of eliminating air. It should be noted that the reason for heating with infrared light is that the procedure is uncomplicated from an equipment standpoint.
Furthermore, it is characterized in that to release air and foreign matter composed of dust and moisture suspended in the air inside the resin while or after it is applied, vibrations are applied to the resin using ultrasonic waves of at least 20 KHz or megasonic waves of at least 1 MHz.
Moreover, it is characterized in that during or after the application of the resin, air therein is released by placing the resin in an environment that is below atmospheric pressure, for example 0.5 atm, preferably 0.1 atm, and more preferably 0.01 atm or less.
Furthermore, it is characterized in that during or after the application of the resin, a velocity of 1 g or 2 g, for example, is applied to the resin to expel air therein.
Furthermore, it is characterized in that during or after the application of the resin to the injection port, the resin is wiped off and reapplied at least twice.
Furthermore, it is characterized in that during or after the application of the resin, air inside the resin is expelled by applying an acceleration to it.
Furthermore, it is characterized in that an acrylic or epoxy based UV curable resin is used as the resin. This makes it possible to freely set the timing at which the resin is cured and also the curing speed becomes fast.
The other inventions of this inventive group are taken from a product standpoint.
In a second inventive group, an anaerobic resin is used for the sealing resin. Here, xe2x80x9canaerobic resinxe2x80x9d means a resin that does not cure when exposed to air, but is cured by the blockage of air at a tiny space. Anaerobic resins are generally used in thread locks, for example, and there are also some that are cured by blocking out air and pressing or heating.
The principle behind this is that by blocking out air, a dimetacrylate is polymerized to polyacrylate and cured. Thus, a polymer is formed on the adhesive surface and creates a powerful adhesive force that reaches its maximum strength several hours after air has been blocked out. Accordingly, a characteristic of anaerobic resins is that they do not require the irradiation of UV light and that curing discrepancies caused by impurities do not easily occur therein.
The second major inventive group includes eight different inventive groups, wherein each inventive group shares a common object in the elimination of the so-called black spots in in-plane electric field mode liquid crystal elements in a broad sense as described above.
It was found that conventional technologies have lacked the effect of preventing black display over extended periods of time, because generally, as shown in FIG. 5, for example, the substrate on the color filter side conventionally has been given the configuration of a conductive layer such as ITO on its top surface, then a glass substrate, a light-blocking layer, a color filter, an over-coating layer, and an orientation film and there are no sites at which the electrodes (conductive substances) are exposed, so that ions or ionized components, which are the cause of black spot defects, are not recovered at all by the color filter side substrate. Accordingly, ions and the like are reliably, and almost entirely, eliminated by some sort of means.
First, in the first inventive group, the fact is exploited that when in in-plane electric field mode liquid crystal elements the total thickness of the insulating layer (film) and the orientation film on the electrodes is extremely thin, the ions and charges in the liquid crystal layer are eliminated through narrow holes, for example, occurring in the insulating film, and that as a result, black spots substantially no longer occur.
A first invention of this inventive group is characterized in that there is a third layer, between a metal layer composed of the electrodes or the signal lines and the liquid crystal layer, which is made of an insulating layer and an orientation film, or a protective film, for example, that may also serve as these films, and there are regions in which the thickness of the insulating layer and the orientation film together is less than 1000 xc3x85 and preferably less than 500 xc3x85. Here, an electrode in a pure in-plane electric field mode element refers to the pixel electrode and the storage electrode or common electrode associated (accompanying) therewith. In-plane electric field elements falling under a broader definition, such as HS, further include other electrodes, for example. Also, it is even better if the total film thickness of the insulating layer and the orientation film, for example, between the pixel electrode and the liquid crystal layer and the common electrode and the liquid crystal layer is less than 500 xc3x85, or if there are sections without these layers. It should be noted that if there is no orientation film or if there are regions in which there is partially no orientation film, then in these areas it may be preferable that some other orienting means has been devised. Of course, if below a black matrix (opposite the user side), for example, then such measures are not necessary. Moreover, in line with future technological advances, a liquid crystal material that does not require an orientation film may also be used.
Hereinafter, in the inventions, Similarly, it is characterized in that the light-blocking film, such as a black matrix, is conductive. Furthermore, it is characterized in that this conductive light-blocking film is formed on the opposing substrate. Furthermore, it is characterized in that the orientation film or the protective film are films of a conductive substance.
Thus, ions and charges in the liquid crystal are shifted and ions or charges in the liquid crystal molecules and the liquid crystal layer are eliminated and the misalignment, for example, of liquid crystal molecules at defective insulating portions, for example, is also eliminated, and thus, a favorable display is attained.
In addition to the above, for example an insulating film for preventing short circuits or a protective film also serving as an insulator is of course formed on the switching element and on electrodes and lines in portions unrelated to achieving the effects of the present invention. Of course, to achieve the operations and effects of the other inventive groups, it is possible to partially not form the protective film, for example. Also, if a configuration in which a specific potential is applied to the conductive light-blocking film is adopted, this is even better.
Similarly, it is characterized in that the process for manufacturing the in-plane electric field mode liquid crystal element includes a step for applying an orientation film and a step for removing the orientation film directly below the black matrix portion, which is not related to display quality, or on a center portion thereof.
Similarly, it is characterized in that after the step for applying the orientation film there is an etching step for removing a portion of the orientation film and a step for orienting the orientation film remaining after the etching step by irradiating UV light, for example.
Similarly, it is characterized in that the orientation film is rubbed and at least a portion of the orientating film is stripped off on the electrodes or wiring (including not just entirely stripping it off but also removing only the top portion (liquid crystal layer side) and forming fine holes or cracks). By setting the pushed-in amount to at least 0.5 mm as one condition during rubbing, the orientation film is more easily stripped off and even better results can be obtained.
In a second inventive group, the focus was on eliminating ions with a neutralization electrode.
In a first invention of this inventive group, apart from the conductive layers of the source signal line, the gate signal line, the pixel electrode, the common electrode, and the common line, for example, which in most cases are in principle composed of a metal, a neutralization electrode made of a conductive substance is provided at a location, which, of course, in principle does not affect the display, in direct contact with the liquid crystal layer or in indirect contact therewith via the orientation layer (film).
Now, the cause of black dot nonuniformities lies in the fact that created ions are not neutralized and thus the ion concentration in the liquid crystal near defect portions increases, which in turn lowers voltage holding ratio. However, if there is a neutralization electrode that is directly exposed to the liquid crystal layer or is in electrical communication with the liquid crystal layer via an orientating film made of a conductive substance, then electrons can once again be given to an electrode at the neutralization electrode, so that the ion concentration near the defective portions in the insulating layer does not increase very much and drops in voltage holding ratio are minimized, and in turn, the occurrence of black spot nonuniformities can be suppressed.
Hereinafter, in the various inventions, a neutralization electrode is formed in contact with the liquid crystal layer or the orientation layer, and a means for supplying to the neutralization electrode a potential that is positive with respect to the gate signal line is provided.
Accordingly, generated anions are more effectively neutralized and the occurrence of black spot nonuniformities can be suppressed.
Also, in another invention, a neutralization electrode is formed along the gate signal line and in contact with the liquid crystal layer or the orientation layer, and a means for supplying to the neutralization electrode a potential that is positive with respect to the gate signal line is provided.
Accordingly, generated anions can be more effectively neutralized before they diffuse from anion generation source into the pixel.
Moreover, a neutralization electrode is formed, along the gate signal line and in contact with the liquid crystal layer or the orientation layer, on the substrate in opposition to the substrate on which the gate signal line is formed, and a means for supplying to the neutralization electrode a potential that is positive with respect to the gate signal line is provided.
Thus, the spacing to the gate signal line is widened, so that parasitic capacitances formed between the neutralization electrode and the gate signal line can be reduced and the effect of parasitic capacitances on gate signal delay is eliminated.
Also, in a further invention, a neutralization electrode is formed, in contact with the liquid crystal layer or the orientation layer, on the substrate in opposition to the substrate on which the gate signal line is formed, a means for supplying to the neutralization electrode a potential that is positive with respect to the gate signal line is provided, and the neutralization electrode serves as a light-blocking layer, such as the black matrix, or a portion thereof.
Thus, the neutralization electrode also serves as the black matrix, for example, and thus the number of steps for forming this electrode can be reduced.
In addition to the above, the conductive light-blocking film can suitably be Cr, Ti, graphite, or a conductive resin, or have a two-layered structure of molybdenum oxide and molybdenum. Furthermore, the neutralization electrode can of course be formed in the direction of the source line or the gate line at the same time these lines are formed, for example, to achieve a reduction in the number of necessary production steps.
Also, it is of course possible to adopt a structure in which the neutralization electrode is given a predetermined potential.
The third inventive group is characterized in that it includes an open portion (exposed portion or portion without insulating film) and a neutralization electrode on the opposing substrate.
In a first invention of this inventive group, there is a site or region on at least one of the electrodes including the pixel electrode, the common electrode, and the signal line electrode, where the insulating film has at least partially not been formed, and at this portion the electrode is in contact with the liquid crystal either directly of via only the orientation film, and moreover a neutralization electrode is formed on the substrate side where the pixel electrode and the common electrode have not been formed and there are either sites on the neutralization electrode where the insulating film has not been formed or the insulating film has not been formed on the neutralization electrode at all.
With the aforementioned configuration, there is a portion where a potential other than that of the gate has been exposed, so that ions that are unevenly distributed in the gate potential portion give (or are given) electrons to the electrode at the portion where a potential other than that of the gate has been exposed and are therefore deionized and eliminated. Thus, an uneven distribution of ions does not occur and the occurrence of black spot nonuniformities can be suppressed.
In particular, because there are sites on both substrates (the array side substrate and the opposing side substrate) where the insulating film has not been formed, the ions are deionized at both substrates, so that there is an even greater effect in preventing black dot nonuniformities from occurring.
Also, the specific resistance of the liquid crystal injected into the liquid crystal panel has been made less than 1013 xcexa9 cm.
Thus, the problem of display burn-in (in which after a certain pattern has been displayed for a long period of time, that pattern is retained even after switching to another pattern) can be inhibited.
Furthermore, it is characterized in that a positive potential with respect to the minimum voltage level of the scanning line is applied to the neutralization electrode.
Thus, ions that have been generated can be effectively deionized.
Also, the neutralization electrode is set to (substantially) the same potential as the common electrode.
Consequently, ions that have been generated can be more effectively deionized and black dot nonuniformities can be inhibited. Also, if the neutralization electrode is set to the same potential as the common electrode, then there is no need to provide a special potential supply means for the neutralization electrode, and therefore its structure/manufacturing process can be simplified.
Furthermore, it is characterized in that the neutralization electrode also serves as the black matrix or the color filter.
Furthermore, various materials for the orientation film have been considered.
Moreover, the liquid crystal panel is provided with a switching element, such as a TFT, and for example an insulating film is formed above this switching element.
Thus, deterioration of the switching element, such as a transistor or a varistor, can be prevented.
In the fourth inventive group, the focus was on neutralizing the liquid crystal by the presence of an open portion in the insulating film.
A first invention of this inventive group is characterized in that the pixel electrode and the opposing electrode are not formed in the same layer but instead, for example, an insulting film is formed on the opposing electrode, which is lower (and opposite the liquid crystal side), but is not formed at all on the higher pixel electrode.
With this configuration, a potential other than that of the gate is exposed, so that ions that are unevenly distributed in the gate potential portion are diffused into the exposed portion of the conductive layer and deionized, so that a liquid crystal panel of a favorable display quality without display nonuniformities can be obtained.
Moreover, since there is no insulating film on the opposing electrode there is also no increase in short-circuit defects.
Furthermore, it is characterized in that the pixel electrode and the opposing electrode are not formed in the same layer and the insulating film is formed on the pixel electrode but is not formed above the opposing electrode at all.
Also with this configuration, a liquid crystal panel of favorable display quality can be obtained without an increase in short-circuit defects.
Furthermore, as other inventive groups, it is characterized in that the specific resistance of the liquid crystal injected into the liquid crystal panel is less than 1013 xcexa9 cm.
Thus, the phenomenon of display burn-in can be suppressed.
Furthermore, it is characterized in that the insulating film is formed over (on the liquid crystal side) the switching element, the signal line, and the scanning line.
Thus, deterioration of the transistor, for example, can be prevented, and these portions are protected.
Furthermore, it is characterized in that there is an insulating film at a portion along the rubbing direction.
With this configuration, the insulating film does not get in the way during rubbing, and therefore a liquid crystal panel of a favorable display quality is achieved.
A fifth inventive group is characterized in that at least a portion of at least the liquid crystal side surface of the light-blocking layer (film) or black matrix has a structure of protrusions/recesses.
A first invention of this inventive group is characterized in that the pixel electrode, the common electrode, the signal line, and the scanning line, for example, are formed on one of the substrates, and a black matrix or a light-blocking film such as a light-blocking layer for preventing semiconductor malfunction and for protection, for example, is formed on the substrate side on which the pixel electrode, for example, has not been formed, and this light-blocking film has a protrusion/recess structure in at least its liquid crystal layer side surface.
With this configuration, ions that are unevenly distributed in the gate potential portion give electrons at the portion (the black matrix portion, for example) where a potential other than that of the gate has been exposed and thus are deionized, so that an uneven distribution of ions does not occur and the occurrence of black dot nonuniformities can be suppressed. Particularly since protrusions/recesses have been formed into the liquid crystal side surface of the black matrix, for example, the surface area for recovering ions increases without a change in the numerical aperture and a sufficient effect can be achieved.
Furthermore, the various inventions are characterized in that a light-blocking film such as a black matrix is formed on the substrate side where the pixel electrode has been formed on the opposing substrate side where the pixel electrode has not been formed, and the surface of the light-blocking has a protrusions/recess structure.
With this configuration, an operation similar to the previous invention are achieved and similar effects thereto are realized.
Furthermore, a margin for adhering becomes unnecessary and an increased numerical aperture can be achieved when the black matrix, for example, is formed on the substrate side on which the pixel electrode is formed (array side).
Furthermore, it is characterized in that a neutralization electrode is formed on the substrate side where the pixel electrode etc. has not been formed or on the substrate where the pixel electrode etc. has been formed, and the surface of the neutralization electrode has a protrusion/recess structure.
With this configuration, an uneven distribution of ions does not occur and the occurrence of black dot nonuniformities can be suppressed. Particularly since the surface of the neutralization electrode is provided with protrusions/recesses, there is a large surface area for recovering ions and a sufficient effect can be achieved.
Furthermore, it is characterized in that the surface of the opposing electrode has a protrusion/recess structure.
With this configuration, in liquid crystal modes using an oblique electric field (if a precautionary note is to be made, those are included in the in-plane electric field format), ions that are unevenly distributed in the gate potential portion give electrons to the electrode at the portion where a potential other than that of the gate has been exposed and are thus deionized, so that an uneven distribution of ions does not occur and the occurrence of black dot nonuniformities can be suppressed. In particular, since the surface of the opposing electrode is provided with protrusions/recesses, there is a large surface area for recovering ions and a sufficient effect can be achieved.
Furthermore, it is characterized in that the light-blocking film, such as the black matrix, is conductive.
With this configuration, ions that are unevenly distributed in the gate potential portion give electrons to the electrode at the portion where a potential other than that of the gate has been exposed and are thus deionized, so that the occurrence of black dot nonuniformities can be suppressed.
Furthermore, it is characterized in that the specific resistance of the liquid crystal injected into the panel of the liquid crystal element is less than 1013 xcexa9 cm.
Thus, as is in the other inventive groups, the phenomenon of display burn-in is suppressed.
Furthermore, it is also characterized in that at least the liquid crystal side surface of the light-blocking film, such as a black matrix, of a color filter side portion used in the image display device has a protrusion/recess structure and preferably has a structure with many holes and with protrusions/recesses.
With this configuration, an uneven distribution of ions does not occur and the occurrence of black dot nonuniformities can be suppressed.
Furthermore, it is characterized in that the difference between the protrusions and the recesses of the protrusion/recess structure is at least 0.1 xcexcm, and preferably at least 0.3 xcexcm.
With this configuration, a large surface area for recovering ions can be secured, so that a sufficient effect is attained.
Furthermore, it is characterized in that the light-blocking film or the neutralization electrode or both are in contact with the liquid crystal either directly or via the orientation film. Thus, ions can be recovered through the small holes in the orientation film or can be recovered directly.
With this configuration, ions can be reliably recovered.
In a sixth inventive group, the principle is that it has a conductive light-blocking film (layer).
A first invention in this inventive group is characterized in that the light-blocking film is in contact with the liquid crystal layer or in particular is in contact with the liquid crystal layer via a conductive orientation film, in a liquid crystal element in which liquid crystal is sandwiched between a pair of substrates, a pixel electrode and a common electrode are formed on one of these substrates, voltage is applied between the pixel electrode and the common electrode to drive the liquid crystal, and there is a conductive light-blocking film on the other substrate.
Furthermore, it is characterized in that there is a region where the light-blocking layer is in contact with the liquid crystal in a stripe shape extending in the direction of the signal line or the scanning line, or in a lattice shape extending in the direction of the signal line or the scanning line.
Therefore, the light-blocking film can also serve as a black matrix, for example, and there is an increase in numerical aperture.
The conductive light-blocking film used in the liquid crystal element can be any material that is light-blocking and conductive, but using CR, Ti, or a conductive resin results in higher light-blocking properties, which is better. Additionally, if the light-blocking film is an organic conductive film it can be produced easily.
Furthermore, it is characterized in that the light-blocking film, or wiring extending from the light-blocking film and of a potential substantially the same as that of the light-blocking film, and the common electrode, or wiring extending from the common electrode and of a potential substantially the same as that of the common electrode, are electrically connected between the substrate pair by at least one or more conducing substances.
Furthermore, it is characterized in that the light-blocking film or wiring extending from the light-blocking film and the common electrode, or wiring extending from the common electrode and of a potential substantially the same as that of the common electrode, are electrically connected between the substrate pair by at least one or more conducing substances.
Furthermore, it is characterized in that, in a liquid crystal element having a light-blocking film and an over-coating layer, a photosensitive material is used for the over-coating layer, and the over-coating layer on the conductive light-blocking layer is stripped off by photolithography to produce a region on the light-blocking film without the over-coating layer.
Other inventions are characterized in that substantially the same potential is applied to the conductive light-blocking film and the common electrode.
The seventh inventive group is characterized in having a light-blocking layer (film) on the opposing substrate and an opening.
A first invention in this inventive group is characterized in that a conductive substance, for example, for recovering ions is formed on both substrates in an in-plane electric field mode liquid crystal element in which liquid crystal is sandwiched between a pair of substrates, a pixel electrode a common, a signal line electrode, and a scanning line electrode are formed on at least one of these substrates, and voltage is applied between the pixel electrode and the common electrode to change the alignment of the liquid crystal molecules.
With this configuration, ions that are unevenly distributed in the gate potential portion give electrons to the electrode at the portion where a potential other than that of the gate has been exposed and are thus deionized, so that an uneven distribution of ions does not occur and black dot nonuniformities can be kept from generating.
Furthermore, it is characterized in that there is a site on at least one of the pixel electrode, the common electrode, and the single line electrode where the insulating film has at least partially not been formed, the electrode is in contact with the liquid crystal through this portion without the insulating film either via the orientation film or directly, a conductive black matrix is formed on the substrate side on which the pixel electrode and the common electrode have not been formed, and a portion or all of the conductive black matrix in the display region is in direct contact with either the orientation film or the liquid crystal.
With this configuration, a potential other than that of the gate is exposed, so that ions that are unevenly distributed in the gate potential portion give electrons to the electrode at the portion where a potential other than that of the gate has been exposed and are deionized, and thus an uneven distribution of ions does not occur.
In particular, since there is a site on both substrates (array side substrate and opposing side substrate) where the insulating film has not been formed, the ions are deionized at both substrate sides, so that the occurrence of black dot nonuniformities can be suppressed.
Furthermore, the insulating film has not been formed on the pixel electrode at all, and where the insulating film has not been formed, the pixel electrode is in contact with the liquid crystal via only the orientation film or is in direct contact with the liquid crystal. Also, a conductive black matrix has been formed on the substrate side on which the pixel electrode and the common electrode have not been formed, and part or all of the conductive black matrix in the display region is in direct contact with either the orientation film or the liquid crystal.
With this configuration, the occurrence of black dot nonuniformities can be suppressed.
Furthermore, it is characterized in that the insulating film has not been formed on the common electrode at all, and the common electrode is in contact with the liquid crystal via only the orientation film or is in direct contact with the liquid crystal through this portion where the insulating film has not been formed. Also, a conductive black matrix has been formed on the substrate on which the pixel electrode and the common electrode have not been formed, and part or all of the black matrix is in direct contact with either the orientation film or the liquid crystal.
With this configuration, the insulating film has not been formed on the common electrode at all and the conductive black matrix is formed on the opposing substrate side, so that the occurrence of black dot nonuniformities can be suppressed because ions are eliminated.
Furthermore, the insulating film has not been formed at all on either the pixel electrode or the common electrode, and the pixel electrode and the common electrode are in contact with the liquid crystal via only the orientation film or are in direct contact with the liquid crystal at these portion without the insulating film. Also, a conductive black matrix has been formed on the substrate side on which the pixel electrode, etc., has not been formed, and part or all of the black matrix is in direct contact with either the orientation film or the liquid crystal.
With this configuration, the occurrence of black dot nonuniformities can be suppressed (however, because there is no insulating film on the pixel or common electrodes, short-circuits easily occur between these electrodes).
Also, like in the other inventive groups, making the specific resistance of the liquid crystal injected into the liquid crystal element smaller than 1013 xcexa9 cm, the phenomenon of display burn-in (in which after a certain pattern has been displayed for a long period of time that pattern is retained even after switching to another pattern) was suppressed.
A switching element is formed in the liquid crystal element in order to drive the element, and an insulating film is provided thereon. Thus, deterioration of the semiconductor, for example, can be prevented.
Furthermore, it is characterized in that a positive potential with respect to the minimum voltage level of the scanning line is applied to the black matrix.
With this configuration, generated ions can be more effectively deionized, and the occurrence of black dot nonuniformities can be suppressed.
Furthermore, it is characterized in that the black matrix has been set to a substantially the same potential as that of the common electrode. Accordingly, generated ions can be more effectively deionized, and the occurrence of black dot nonuniformities can be suppressed. Setting the black matrix to the same potential as the common electrode eliminates the need to provide a special potential supplying means for the black matrix, and thus the structure/production process can be simplified.
Furthermore, the conductive black matrix is formed by a conductive resin. For this reason it can be fabricated in the same step as that for forming the color filter. Moreover, in contrast to forming a metal such as Cr, which requires elevated temperature formation, this black matrix can be formed after the color filter has been formed. Accordingly, the black matrix can be formed at a site in contact with the orientation film or the liquid crystal.
Furthermore, it is characterized in that the substrates of the liquid crystal element are held at a certain spacing by forming columns at a specific location as spacers. By regulating in this way, the spacers can be selectively established at spots where the top and bottom substrates are not easily short-circuited, and thus short-circuits do not occur easily even if conductive substances are formed onto both substrates.
In an eighth inventive group, the orientation film or at least a surface portion thereof and at least a portion of the surface of the neutralization electrode, for example, has a cell structure (sponge structure having spaces with an extremely small diameter) caused by a foaming agent. Thus, the absorption of generated ions is achieved.